155 lines
6.4 KiB
Markdown
155 lines
6.4 KiB
Markdown
Katenary is a tool to help transforming `docker-compose` files to a working Helm Chart for Kubernetes.
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> **Important Note** Katenary is a tool to help building Helm Chart from a docker-compose file, but docker-compose doesn't propose as many features as what can do Kubernetes. So, we strongly recommend to use Katenary as a "bootstrap" tool and then to manually enhance the generated helm chart.
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This project is partially made at [Smile](https://smile.eu)
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# Install
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If you've got `podman` or `docker`, you can build `katenary` by using:
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```bash
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make build
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```
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You can then install it with:
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```bash
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make install
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```
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It will use the default PREFIX (`~/.local/`) to install the binary in the `bin` subdirectory. You can force the PREFIX value at install time, but maybe you need to use "sudo":
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```bash
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sudo make install PREFIX=/usr/local
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```
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# Tips
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We strongly recommand to add the "completion" call to you SHELL using the common bashrc, or whatever the profile file you use.
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E.g. :
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```bash
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# bash in ~/.bashrc file
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source <(katenary completion bash)
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# if the documentation breaks a bit your completion:
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source <(katenary completion bash --no-description)
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# zsh in ~/.zshrc
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source <(helm completion zsh)
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# fish in ~/.config/fish/config.fish
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katenary completion fish | source
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# powershell (as we don't provide any support on Windows yet, please avoid this...)
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```
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# Usage
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```
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Katenary aims to be a tool to convert docker-compose files to Helm Charts.
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It will create deployments, services, volumes, secrets, and ingress resources.
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But it will also create initContainers based on depend_on, healthcheck, and other features.
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It's not magical, sometimes you'll need to fix the generated charts.
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The general way to use it is to call one of these commands:
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katenary convert
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katenary convert -f docker-compose.yml
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katenary convert -f docker-compose.yml -o ./charts
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In case of, check the help of each command using:
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katenary <command> --help
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or
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"katenary help <command>"
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Usage:
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katenary [command]
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Available Commands:
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completion Generate the autocompletion script for the specified shell
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convert Convert docker-compose to helm chart
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help Help about any command
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show-labels Show labels of a resource
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version Display version
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Flags:
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-h, --help help for katenary
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Use "katenary [command] --help" for more information about a command.
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```
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Katenary will try to find a `docker-compose.yaml` or `docker-compose.yml` file inside the current directory. It will check *the existence of the `chart` directory to create a new Helm Chart inside a named subdirectory. Katenary will ask you if you want to delete it before recreating.
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It creates a subdirectory inside `chart` that is named with the `appname` option (default is `MyApp`)
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> To respect the ability to install the same application in the same namespace, Katenary will create "variable" names like `{{ .Release.Name }}-servicename`. So, you will need to use some labels inside your docker-compose file to help katenary to build a correct helm chart.
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What can be interpreted by Katenary:
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- Services with "image" section (cannot work with "build" section)
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- **Named Volumes** are transformed to persistent volume claims - note that local volume will break the transformation to Helm Chart because there is (for now) no way to make it working (see below for resolution)
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- if `ports` and/or `expose` section, katenary will create Services and bind the port to the corresponding container port
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- `depends_on` will add init containers to wait for the depending service (using the first port)
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- `env_file` list will create a configMap object per environemnt file (⚠ todo: the "to-service" label doesn't work with configMap for now)
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- some labels can help to bind values, for example:
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- `katenary.io/ingress: 80` will expose the port 80 in a ingress
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- `katenary.io/to-service: VARNAME` will convert the value to a variable `{{ .Release.Name }}-VARNAME` - it's usefull when you want to pass the name of a service as a variable (think about the service name for mysql to pass to a container that wants to connect to this)
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Exemple of a possible `docker-compose.yaml` file:
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```yaml
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version: "3"
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services:
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webapp:
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image: php:7-apache
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environment:
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# note that "database" is a service name
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DB_HOST: database
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expose:
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- 80
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depends_on:
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# this will create a init container waiting for 3306 port
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# because it's the "exposed" port
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- database
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labels:
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# explain to katenary that "DB_HOST" value is variable (using release name)
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katenary.io/env-to-service: DB_HOST
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# expose the port 80 as an ingress
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katenary.io/ingress: 80
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database:
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image: mariadb:10
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env_file:
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# this will create a configMap
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- my_env.env
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environment:
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MARIADB_ROOT_PASSWORD: foobar
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labels:
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# no need to declare this port in docker-compose
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# but katenary will need it
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katenary.io/ports: 3306
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```
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# Labels
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These labels could be found by `katenary show-labels`, and can be placed as "labels" inside your docker-compose file:
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```
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katenary.io/secret-envfiles : set the given file names as a secret instead of configmap
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katenary.io/ports : set the ports to expose as a service (coma separated)
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katenary.io/ingress : set the port to expose in an ingress (coma separated)
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katenary.io/env-to-service : specifies that the environment variable points on a service name (coma separated)
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katenary.io/configmap-volumes : specifies that the volumes points on a configmap (coma separated)
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katenary.io/same-pod : specifies that the pod should be deployed in the same pod than the given service name
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katenary.io/empty-dirs : specifies that the given volume names should be "emptyDir" instead of persistentVolumeClaim (coma separated)
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katenary.io/healthcheck : specifies that the container should be monitored by a healthcheck, **it overrides the docker-compose healthcheck**.
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You can use these form of label values:
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- "http://[not used address][:port][/path]" to specify an http healthcheck
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- "tcp://[not used address]:port" to specify a tcp healthcheck
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- other string is condidered as a "command" healthcheck
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```
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