### Workload FlexVolume Setup

Source: https://github.com/projectcalico/calico/blob/master/pod2daemon/README.md

Example configuration for a Kubernetes workload demonstrating how to set up the FlexVolume driver for pod-to-daemon communication.

```yaml
...
     containers:
        volumeMounts:
        - mountPath: /tmp/udsver
          name: test-volume
      volumes:
        - name: test-volume
          flexVolume:
            driver: nodeagent/uds

```

--------------------------------

### Build and Install confd from Source

Source: https://github.com/projectcalico/calico/blob/master/confd/docs/installation.md

Compile confd from source code and install it on the system.

```bash
$ ./build
$ sudo ./install
```

--------------------------------

### Install Update Tools

Source: https://github.com/projectcalico/calico/blob/master/typha/README.md

Installs additional Go tools required for building Typha. Run this once before building.

```bash
make update-tools
```

--------------------------------

### Node-to-Node BGP Mesh Configuration Example

Source: https://github.com/projectcalico/calico/blob/master/libcalico-go/docs/data-model.md

JSON blob for controlling the automatic setup of a full node-to-node BGP mesh. If missing, it is enabled by default.

```json
{
  "enabled": true|false
}
```

--------------------------------

### Install Ginkgo and Glide

Source: https://github.com/projectcalico/calico/blob/master/node/README.md

Install the Ginkgo testing framework and Glide dependency manager for Golang. These are required for running 'fv' packaged scoped tests.

```bash
go get -u github.com/Masterminds/glide
go get -u github.com/onsi/ginkgo/ginkgo
```

--------------------------------

### Example: Run confd in Noop Mode with One-Time Execution

Source: https://github.com/projectcalico/calico/blob/master/confd/docs/noop-mode.md

This example demonstrates running confd with both the '-onetime' and '-noop' flags. Noop mode ensures that even if changes are detected, no files will be modified.

```bash
confd -onetime -noop
```

--------------------------------

### Install Tigera Operator Helm Chart

Source: https://github.com/projectcalico/calico/blob/master/charts/tigera-operator/README.md

Installs the Tigera Operator Helm chart into the specified namespace.

```bash
helm install calico projectcalico/tigera-operator --namespace tigera-operator
```

--------------------------------

### Run Unit Tests with Watch Mode

Source: https://github.com/projectcalico/calico/blob/master/felix/README.md

Start a ginkgo watch process that automatically re-runs relevant unit tests as files are updated. Requires ginkgo to be installed.

```bash
make ut-watch
```

--------------------------------

### Allocation Block Configuration Example

Source: https://github.com/projectcalico/calico/blob/master/libcalico-go/docs/data-model.md

JSON blob for Allocation Block configuration, detailing CIDR, host affinity, address allocations, and attributes.

```json
{
    "cidr": "192.168.0.0/24",
    "affinity": "host:calico-host-01",
    "allocations": [0, 0, 0, 1, 2, 2, nil, nil, nil, nil, ...],
    "attributes": [
        {
            "primary": "0cd47986-24ad-4c00-b9d3-5db9e5c02028",
            "secondary": {
                "container-id": "ba11f1de-fc4d-46fd-9f15-424f4ef05a3a",
                "email": "spike@projectcalico.org"
            }
        },
        {
            "primary": "3465987ac-8975-987qr8789725875-98275",
            "secondary": {
                "container-name": "sandy_sabin",
                "email": "spike@projectcalico.org"
            }
        },
        {
            "primary": "adf4589-11ab-c519-af11-098fade2190798",
            "secondary": {
                "rack": "01"
            }
        }
    ] 
}
```

--------------------------------

### Add keys to etcd for complex example

Source: https://github.com/projectcalico/calico/blob/master/confd/docs/templates.md

Demonstrates creating nested directories and setting values within etcd, preparing data for a more complex template.

```bash
etcdctl mkdir /services/web/cust1/
etcdctl mkdir /services/web/cust2/
etcdctl set /services/web/cust1/2 '{"IP": "10.0.0.2"}'
etcdctl set /services/web/cust2/2 '{"IP": "10.0.0.4"}'
etcdctl set /services/web/cust2/1 '{"IP": "10.0.0.3"}'
etcdctl set /services/web/cust1/1 '{"IP": "10.0.0.1"}'
```

--------------------------------

### IP Pool Configuration Example

Source: https://github.com/projectcalico/calico/blob/master/libcalico-go/docs/data-model.md

JSON blob for IP pool configuration, including CIDR, IPIP device name, and masquerade setting.

```json
{
  "cidr": "<CIDR of pool - eg. 192.168.0.0/16 or fd80:24e2:f998:72d6::/64>",
  "ipip": "<IPIP device name if IPIP configured for the pool - usually tunl0>",
  "masquerade": true|false
}
```

--------------------------------

### JSON Allocation Handles Configuration Example

Source: https://github.com/projectcalico/calico/blob/master/libcalico-go/docs/data-model.md

JSON blob for Allocation Handle configuration, mapping Allocation Block CIDRs to the count of associated allocations.

```json
{
    "id": <string handle ID>,
    "block": {
        "192.168.10.0/24": 4,
        "2001:abcd:def0::/120": 3
    }
}
```

--------------------------------

### Dump Conntrack Entries with nfnetlink

Source: https://github.com/projectcalico/calico/blob/master/felix/nfnetlink/README.md

This example demonstrates how to dump all conntrack entries to the screen using the nfnetlink package. It requires a handler to process each entry.

```go
package main

import (
        "fmt"

        "github.com/tigera/nfnetlink"
)

type Handler struct {
        count int
}

func (h *Handler) HandleConntrackEntry(cte nfnetlink.CtEntry) {
        fmt.Printf("%+v\n", cte)
        h.count++
}

func ctdump() {
        handler := &Handler{}
        err := nfnetlink.ConntrackList(handler.HandleConntrackEntry)
        if err != nil {
                fmt.Println("Error: ", err)
        }
        fmt.Printf("Num entries returned %+v\n", handler.count)
}

func main() {
        fmt.Println("Running")
        ctdump()
}
```

--------------------------------

### Catalina start script with CATALINA_OPTS

Source: https://github.com/projectcalico/calico/blob/master/confd/docs/tomcat-sample.md

A minimal shell script to set CATALINA_OPTS environment variables for Tomcat memory settings, intended to be managed by confd.

```sh
#!/bin/sh
CATALINA_OPTS="-Xms{{getv "/Xms"}} -Xmx{{getv "/Xmx"}}" /usr/local/tomcat/bin/catalina.sh start
```

--------------------------------

### RapidClient Example Scenarios

Source: https://github.com/projectcalico/calico/blob/master/e2e/images/rapidclient/README.md

Illustrates practical applications of RapidClient, including testing Maglev load balancing with consistent source ports, setting custom request timeouts, and enabling verbose mode for debugging.

```bash
# Test Maglev load balancing with consistent source port
./rapidclient -url "http://service-ip:8080/shell?cmd=hostname" -port 12345

```

```bash
# Test with custom timeout
./rapidclient -url "http://service-ip:8080/api/health" -timeout 10s

```

```bash
# Verbose mode for debugging
./rapidclient -url "http://service-ip:8080/shell?cmd=hostname" -port 12345 -v

```

--------------------------------

### Display Release Tool Help

Source: https://github.com/projectcalico/calico/blob/master/release/README.md

Run this command to see the available options and usage instructions for the release tool.

```shell
./bin/release --help
```

--------------------------------

### Basic RapidClient Usage

Source: https://github.com/projectcalico/calico/blob/master/e2e/images/rapidclient/README.md

Demonstrates fundamental command-line operations for RapidClient. Use these examples to send single requests, specify a source port, or enable verbose logging for detailed status and debug information.

```bash
# Send a single request to a service
./rapidclient -url "http://10.96.0.1:8080/shell?cmd=hostname"

```

```bash
# Use a specific source port
./rapidclient -url "http://10.96.0.1:8080/shell?cmd=hostname" -port 12345

```

```bash
# Verbose output with status information
./rapidclient -url "http://10.96.0.1:8080/shell?cmd=hostname" -v

```

--------------------------------

### Get Key-Value Pair

Source: https://github.com/projectcalico/calico/blob/master/confd/docs/templates.md

The `get` function retrieves a KVPair by its key. It returns an error if the key is not found.

```go-template
{{with get "/key"}}
    key: {{.Key}}
    value: {{.Value}}
{{end}}
```

--------------------------------

### Example confd Log Messages

Source: https://github.com/projectcalico/calico/blob/master/confd/docs/logging.md

These are example log messages generated by confd, illustrating different informational events during its operation.

```Bash
2013-11-03T19:04:53-08:00 confd[21356]: INFO SRV domain set to confd.io
2013-11-03T19:04:53-08:00 confd[21356]: INFO Starting confd
2013-11-03T19:04:53-08:00 confd[21356]: INFO etcd nodes set to http://etcd0.confd.io:4001, http://etcd1.confd.io:4001
2013-11-03T19:04:54-08:00 confd[21356]: INFO /tmp/myconf2.conf has md5sum ae5c061f41de8895b6ef70803de9a455 should be 50d4ce679e1cf13e10cd9de90d258996
2013-11-03T19:04:54-08:00 confd[21356]: INFO Target config /tmp/myconf2.conf out of sync
2013-11-03T19:04:54-08:00 confd[21356]: INFO Target config /tmp/myconf2.conf has been updated

```

--------------------------------

### Example confd.toml Configuration

Source: https://github.com/projectcalico/calico/blob/master/confd/docs/configuration-guide.md

This TOML snippet demonstrates a typical configuration for confd, including backend settings, client certificates, logging level, polling interval, node list, and prefix.

```toml
backend = "etcd"
client_cert = "/etc/confd/ssl/client.crt"
client_key = "/etc/confd/ssl/client.key"
confdir = "/etc/confd"
log-level = "debug"
interval = 600
nodes = [
  "http://127.0.0.1:4001",
]
noop = false
prefix = "/production"
scheme = "https"
srv_domain = "etcd.example.com"

```

--------------------------------

### Get All Matching Key-Value Pairs

Source: https://github.com/projectcalico/calico/blob/master/confd/docs/templates.md

The `gets` function retrieves all KVPairs where the key matches the provided pattern. It returns an error if no keys are found.

```go-template
{{range gets "/*"}}
    key: {{.Key}}
    value: {{.Value}}
{{end}}
```

--------------------------------

### Process Template with StackEngine Backend

Source: https://github.com/projectcalico/calico/blob/master/confd/docs/quick-start-guide.md

Run confd in one-time mode with StackEngine as the backend. Requires an auth token and node address.

```bash
confd -onetime -backend stackengine -auth-token stackengine_api_key -node 192.168.255.210:8443 -scheme https
```

--------------------------------

### Install Calico CRDs

Source: https://github.com/projectcalico/calico/blob/master/charts/tigera-operator/README.md

Installs the Calico Custom Resource Definitions (CRDs) using Helm template and kubectl apply. This is required for Calico versions 3.32 and later.

```bash
helm template calico-crds projectcalico/crd.projectcalico.org.v1 | kubectl apply --server-side -f -
```

--------------------------------

### Calico Installation Settings

Source: https://github.com/projectcalico/calico/blob/master/charts/tigera-operator/README.md

Configures general installation parameters for Calico, including Kubernetes provider and image pull secrets for the operator. Secrets must exist in the tigera-operator namespace.

```yaml
# Configures general installation parameters for Calico. Schema is based
# on the operator.tigera.io/Installation API documented
# here: https://docs.tigera.io/calico/latest/reference/installation/api#installationspec
installation:
  enabled: true
  kubernetesProvider: ""

  # imagePullSecrets are configured on all images deployed by the tigera-operator.
  # secrets specified here must exist in the tigera-operator namespace; they won't be created by the operator or helm.
  # imagePullSecrets are a slice of LocalObjectReferences, which is the same format they appear as on deployments.
  #
  # Example: --set installation.imagePullSecrets[0].name=my-existing-secret
  imagePullSecrets: []

  # Configure the kubelet volume plugin path used by the CSI driver.
  # Set to "None" to disable the CSI driver. If this field is left unset, /var/lib/kubelet is used and CSI is enabled.
  kubeletVolumePluginPath: "None"
```

--------------------------------

### Run Windows Connectivity Tests

Source: https://github.com/projectcalico/calico/blob/master/process/testing/win-connections/README.md

Execute the main script to set up the test environment and run connectivity checks between Linux and Windows nodes. Ensure prerequisites are met before running.

```bash
./run-tests.sh
```

--------------------------------

### Install New Calico Helm Chart

Source: https://github.com/projectcalico/calico/blob/master/charts/tigera-operator/README.md

Install the new Calico helm chart into the 'tigera-operator' namespace after patching existing resources. This command assumes you are upgrading from a version prior to v3.23.0.

```bash
helm install {{site.prodname | downcase}} projectcalico/tigera-operator --version {{site.data.versions[0].title}} --namespace tigera-operator
```

--------------------------------

### BPF Test Matrix Prefix Example

Source: https://github.com/projectcalico/calico/blob/master/felix/design/bpf-tests.md

An example of a matrix prefix used in BPF functional tests to identify dataplane parameter combinations. This format is used to specify configurations for testing.

```text
"ipv4 udp, ct=true, log=debug, tunnel=none, dsr=false"
```

--------------------------------

### Generate Release Notes

Source: https://github.com/projectcalico/calico/blob/master/release/RELEASING.md

Run the make command to collect all release notes for a given version. This will create a file in the 'release-notes/' directory.

```sh
make release-notes
```

--------------------------------

### Install or Upgrade Calico CRDs

Source: https://github.com/projectcalico/calico/blob/master/charts/crd.projectcalico.org.v1/README.md

Use this command to add the Calico Helm repository and then template and apply the CRDs. This method is preferred over `helm install` for CRDs that may exceed size limits.

```bash
helm repo add projectcalico https://docs.tigera.io/calico/charts
helm template calico-crds projectcalico/crd.projectcalico.org.v1 | kubectl apply --server-side -f -
```

--------------------------------

### Build and Test Commands

Source: https://github.com/projectcalico/calico/blob/master/goldmane/CLAUDE.md

Common make targets for building binaries, Docker images, running unit tests, benchmarks, and regenerating code artifacts.

```bash
make build

# Build Docker image
make image

# Run unit tests
make ut

# Run unit tests directly (faster iteration, no Docker)
go test ./...

# Run benchmarks
make benchmark

# Regenerate protobuf
make protobuf

# Regenerate mocks
make gen-mocks
```

--------------------------------

### Selector Expression Examples

Source: https://github.com/projectcalico/calico/blob/master/libcalico-go/docs/data-model.md

Illustrates various ways to construct selector expressions for matching endpoint labels in Calico policies. These examples cover comparisons, set membership, label presence, negation, and logical operations.

```string
type == "webserver" && deployment == "prod"
```

```string
type in {"frontend", "backend"}
```

```string
deployment != "dev"
```

```string
! has(label_name)
```

--------------------------------

### Create Tigera Operator Namespace

Source: https://github.com/projectcalico/calico/blob/master/charts/tigera-operator/README.md

Creates the Kubernetes namespace where the Tigera Operator will be installed.

```bash
kubectl create namespace tigera-operator
```

--------------------------------

### Get parent directory

Source: https://github.com/projectcalico/calico/blob/master/confd/docs/templates.md

Use `dir` to find the parent directory of a given key.

```go-template
{{with dir "/services/data/url"}}
dir: {{.}}
{{end}}
```

--------------------------------

### Create Confd Directory Structure

Source: https://github.com/projectcalico/calico/blob/master/confd/docs/quick-start-guide.md

Create the necessary directories for confd configuration and templates.

```bash
sudo mkdir -p /etc/confd/{conf.d,templates}
```

--------------------------------

### Run Go Unit Tests

Source: https://github.com/projectcalico/calico/blob/master/felix/CLAUDE.md

Executes all Go unit tests using Ginkgo, including coverage. Skips specific packages. Pass GINKGO_ARGS for additional flags.

```bash
make ut
```

--------------------------------

### Get Current Datetime

Source: https://github.com/projectcalico/calico/blob/master/confd/docs/templates.md

The `datetime` function is an alias for `time.Now`, providing the current timestamp.

```go-template
# Generated by confd {{datetime}}
```

--------------------------------

### Get Base Key Name

Source: https://github.com/projectcalico/calico/blob/master/confd/docs/templates.md

The `base` function is an alias for `path.Base`, used to extract the last element of a path.

```go-template
{{with get "/key"}}
    key: {{base .Key}}
    value: {{.Value}}
{{end}}
```

--------------------------------

### Clone Calico API Repository

Source: https://github.com/projectcalico/calico/blob/master/release/RELEASING.md

Clone the projectcalico/api repository to begin API updates. Ensure Github CLI is installed.

```sh
git clone git@github.com:projectcalico/api.git
```

--------------------------------

### Process Template with etcd Backend

Source: https://github.com/projectcalico/calico/blob/master/confd/docs/quick-start-guide.md

Run confd in one-time mode with etcd as the backend.

```bash
confd -onetime -backend etcd -node http://127.0.0.1:4001
```

--------------------------------

### Process Template with Redis Backend

Source: https://github.com/projectcalico/calico/blob/master/confd/docs/quick-start-guide.md

Run confd in one-time mode with Redis as the backend. Specify the node address.

```bash
confd -onetime -backend redis -node 192.168.255.210:6379
```

--------------------------------

### Get XDP Accepted Metadata

Source: https://github.com/projectcalico/calico/blob/master/felix/design/bpf-xdp.md

Retrieves the metadata indicating if a packet was accepted by XDP. This is called in the TC ingress hook.

```c
xdp2tc_get_metadata(skb);
```

--------------------------------

### Get Environment Variable

Source: https://github.com/projectcalico/calico/blob/master/confd/docs/templates.md

The `getenv` function retrieves the value of an environment variable. It returns an empty string if the variable is not set.

```bash
export HOSTNAME `hostname`
```

```go-template
hostname: {{getenv "HOSTNAME"}}
```

--------------------------------

### Build All Calico Images

Source: https://github.com/projectcalico/calico/blob/master/DEVELOPER_GUIDE.md

Run this command from the repository root to build all Calico container images. This process may take time.

```bash
make image
```

--------------------------------

### Build All Calico Binaries

Source: https://github.com/projectcalico/calico/blob/master/DEVELOPER_GUIDE.md

Create binaries for all supported architectures. The output binaries are located in 'bin/' or 'dist/' and follow a standard naming convention.

```bash
make build-all
```

--------------------------------

### Tag List Example

Source: https://github.com/projectcalico/calico/blob/master/libcalico-go/docs/data-model.md

A JSON list of tag strings. Each tag applies to endpoints associated with a policy and can be referenced by rules.

```json
["A", "B", "C", ...]
```

--------------------------------

### Process Template with Environment Variables Backend

Source: https://github.com/projectcalico/calico/blob/master/confd/docs/quick-start-guide.md

Run confd in one-time mode using environment variables as the backend.

```bash
confd -onetime -backend env
```

--------------------------------

### Check Flow Emitter State

Source: https://github.com/projectcalico/calico/blob/master/goldmane/CLAUDE.md

Use this command to check the state of the flow emitter, which is typically active only in Calico Enterprise/Cloud installations.

```bash
kubectl get configmap -n calico-system flow-emitter-state -o yaml
```

--------------------------------

### Open Unit Test Coverage in Browser

Source: https://github.com/projectcalico/calico/blob/master/felix/README.md

Generate unit test coverage statistics and open the report in a web browser. Requires Go and GNU make.

```bash
make cover-browser
```

--------------------------------

### Get Value by Key with Default

Source: https://github.com/projectcalico/calico/blob/master/confd/docs/templates.md

Use `getv` with a default value to retrieve a key's value, returning the default if the key is not found.

```go-template
value: {{getv "/key" "default_value"}}
```