boky/alpine-bootstrap repository overview

⁠About

A basic Alpine image with a few tools to enable you to better start of your work.

Mostly useful for Docker and Kubernetes init containers⁠ as well as debugging your own containers.

If you are missing anything, send in a merge request. Let's just not overdoit, folks. Currently available:

• awk (gawk⁠)
• bash⁠
• busybox⁠ (with aliases for lots of tools...)
• curl⁠ and wget⁠
• gzip⁠, bzip2⁠, and xz⁠
• jq⁠ A lightweight and flexible command-line JSON processor
• kubectl⁠
• libressl⁠ (openssl fork)
• psql⁠ - a PostgreSQL client
• sed⁠
• vim⁠ (who can live without it)

AWS scripts:

• s3 A bash script for downloading secure files from AWS s3 without the need for the full fledged AWS client
• ecr-get-authorization-token A bash script for getting AWS ECR repository authorization token without the need for AWS client.
• ecr-get-login A script that mimics the aws ecr get-login output
• ecr-describe-repositories is a call to Describe Repositories⁠ API
• esc-create-repository is a call to Create Repository⁠ API

⁠AWS

The scripts (e.g. s3 and get-authorization-token) will require you set propery environment variables before invoking them, namely: AWS_ACCESS_KEY_ID, AWS_SECRET_ACCESS_KEY and AWS_REGION. If you're an AWS user, you'll know what they eman.

⁠Usage

export AWS_ACCESS_KEY_ID=xxx 
export AWS_SECRET_ACCESS_KEY=yyy 
export AWS_REGION=eu-central-2 

s3 bucket path/file.ext > file.ext
ecr-get-authorization-token
$(ect-get-login)

⁠Wait for service in Kubernetes

This image also includes a bash script wait-for-service, which will wait for a given service to be up before continuing. It's API/parameter compatible with fabric8-dependency-wait-service⁠ but since it's written in BASH and not GO:

• the image is much smaller
• there's no need to include different binaries for different platforms
• more platforms are automatically supported out of the box (e.g. wherever BASH works)

⁠Environment variables

The following variables can be used to control the service:

⁠Usage

This utility is used as part of the init containers⁠.

Usage:

  wait-for-service [parameters] [tcp://host:port | postgres://[user@]host[:port] | http[s]://host[:port] | ... ] [-- command args]

  wait-for-service will wait for the specified service to be up and running before returning / exiting from the function.
    It will optionally run the command(s) at the end of the line after the commnad completes successfully.

    Available parameters:
    -t | --timeout=TIMEOUT            Script timeout parameter
    -v | --verbose                    Be verbose. 
                                      Alias for DEPENDENCY_LOG_VERBOSE=true
    -q | --quiet                      Be quiet. 
                                      Alias for DEPENDENCY_LOG_VERBOSE=false
    -c | --connection-timeout=TIMEOUT Timeout before the service is deemed inaccessible (default is 5 seconds).
                                      Alias for DEPENDENCY_CONNECT_TIMEOUT
    -p | --poll-interval=INTERVAL     Interval in seconds between polling retries.
                                      Alias for DEPENDENCY_POLL_INTERVAL
    -C | --colo[u]r                   Force colour output.

    tcp://host:port                   Wait for the given service to be available at specified host/port. Uses Netcat.
    postgres://[user@]host[:port]     Wait for PostgreSQL to be available. Uses pg_isready.
    http[s]://host[:port]             Wait for HTTP(s) service to be ready. Uses curl.
    
    -- COMMAND ARGS                   Execute command with args after the test finishes

An example is given below:

spec:
  initContainers:
    - name: web-for-services
      image: "boky/alpine-bootstrap"
      command: [ 'wait-for-service', 'postgres://user@host:port', 'https://whole-url-to-service', 'tcp://host:port', ... ]
      # Or, using the fabric8-compatible symlink
      command: [ 'fabric8-dependency-wait-service-linux-amd64', 'postgres://user@host:port', 'https://whole-url-to-service', 'tcp://host:port', ... ]
      env:
        - name: DEPENDENCY_POLL_INTERVAL
          value: "10"
        - name: DEPENDENCY_LOG_VERBOSE
          value: "false"
        - name: DEPENDENCY_CONNECT_TIMEOUT
          value: "10"

⁠Supported protocols

The following protocols are supported:

• HTTP: Anything that starts with http:// or https:// is considered a HTTP protocol. curl⁠ is used to make a HTTP HEADrequest. Automatically falls back to TCP check if curl is not available. A service is considered up if:

  • It doesn't time out
  • It returns a result in the range 2xx

• POSTGRES: The syntax is: postgres://[<user>@]<host>[:<port>]. The given postgres url is parsed for username, host, and port and passed to the pg_isready⁠ utility. Automatically falls back to TCP check if pg_isready is not avaiable. The db is considered up when pg_isready returns a zero exit code.

• TCP: The syntax is: tcp://<host>:<port>. Netcat⁠ is used to connect to the service. Service is considered up when netcat successfully connects and return a zero exit code. If netcat is not avaialbe, uses /dev/tcp to send open up a port.