mirror of https://github.com/knative/docs.git
Add a helloworld sample for haskell (#316)
* Add a helloworld sample for haskell * Use stack as the build tool * Use scotty as a web framework * Use docker multi-stage build to create a smaller runtime image * Apply review comments on the README.md * Apply language review comments - Fix `service.yaml` indentation - Change heading for sample code recreation
This commit is contained in:
parent
1a48e0bbe8
commit
1b52510c44
|
@ -0,0 +1,6 @@
|
|||
.stack-work/
|
||||
*.cabal
|
||||
*~
|
||||
/.idea/
|
||||
/dist/
|
||||
/out/
|
|
@ -0,0 +1,21 @@
|
|||
# Use the existing Haskell image as our base
|
||||
FROM haskell:8.2.2 as builder
|
||||
|
||||
# Checkout our code onto the Docker container
|
||||
WORKDIR /app
|
||||
ADD . /app
|
||||
|
||||
# Build and test our code, then install the “helloworld-haskell-exe” executable
|
||||
RUN stack setup
|
||||
RUN stack build --copy-bins
|
||||
|
||||
# Copy the "helloworld-haskell-exe" executable to the image using docker multi stage build
|
||||
FROM fpco/haskell-scratch:integer-gmp
|
||||
WORKDIR /root/
|
||||
COPY --from=builder /root/.local/bin/helloworld-haskell-exe .
|
||||
|
||||
# Expose a port to run our application
|
||||
EXPOSE 8080
|
||||
|
||||
# Run the server command
|
||||
CMD ["./helloworld-haskell-exe"]
|
|
@ -0,0 +1,198 @@
|
|||
# Hello World - Haskell sample
|
||||
|
||||
A simple web app written in Haskell that you can use for testing.
|
||||
It reads in an env variable `TARGET` and prints "Hello World: ${TARGET}!". If
|
||||
TARGET is not specified, it will use "NOT SPECIFIED" as the TARGET.
|
||||
|
||||
## Prerequisites
|
||||
|
||||
* A Kubernetes cluster with Knative installed. Follow the
|
||||
[installation instructions](https://github.com/knative/docs/blob/master/install/README.md) if you need
|
||||
to create one.
|
||||
* [Docker](https://www.docker.com) installed and running on your local machine,
|
||||
and a Docker Hub account configured (we'll use it for a container registry).
|
||||
|
||||
## Recreating the sample code
|
||||
|
||||
While you can clone all of the code from this directory, hello world
|
||||
apps are generally more useful if you build them step-by-step. The
|
||||
following instructions recreate the source files from this folder.
|
||||
|
||||
1. Create a new file named `stack.yaml` and paste the following code:
|
||||
|
||||
```yaml
|
||||
flags: {}
|
||||
packages:
|
||||
- .
|
||||
extra-deps: []
|
||||
resolver: lts-10.7
|
||||
```
|
||||
1. Create a new file named `package.yaml` and paste the following code
|
||||
|
||||
```yaml
|
||||
name: helloworld-haskell
|
||||
version: 0.1.0.0
|
||||
dependencies:
|
||||
- base >= 4.7 && < 5
|
||||
- scotty
|
||||
- text
|
||||
|
||||
executables:
|
||||
helloworld-haskell-exe:
|
||||
main: Main.hs
|
||||
source-dirs: app
|
||||
ghc-options:
|
||||
- -threaded
|
||||
- -rtsopts
|
||||
- -with-rtsopts=-N
|
||||
```
|
||||
|
||||
1. Create a `app` folder, then create a new file named `Main.hs` in that folder
|
||||
and paste the following code. This code creates a basic web server which
|
||||
listens on port 8080:
|
||||
|
||||
```haskell
|
||||
{-# LANGUAGE OverloadedStrings #-}
|
||||
|
||||
import Data.Maybe
|
||||
import Data.Monoid ((<>))
|
||||
import Data.Text.Lazy (Text)
|
||||
import Data.Text.Lazy
|
||||
import System.Environment (lookupEnv)
|
||||
import Web.Scotty (ActionM, ScottyM, scotty)
|
||||
import Web.Scotty.Trans
|
||||
|
||||
main :: IO ()
|
||||
main = do
|
||||
t <- fromMaybe "NOT SPECIFIED" <$> lookupEnv "TARGET"
|
||||
scotty 8080 (route t)
|
||||
|
||||
route :: String -> ScottyM()
|
||||
route t = get "/" $ hello t
|
||||
|
||||
hello :: String -> ActionM()
|
||||
hello t = text $ pack ("Hello world: " ++ t)
|
||||
```
|
||||
|
||||
1. In your project directory, create a file named `Dockerfile` and copy the code
|
||||
block below into it.
|
||||
|
||||
```docker
|
||||
# Use the existing Haskell image as our base
|
||||
FROM haskell:8.2.2 as builder
|
||||
|
||||
# Checkout our code onto the Docker container
|
||||
WORKDIR /app
|
||||
ADD . /app
|
||||
|
||||
# Build and test our code, then install the “helloworld-haskell-exe” executable
|
||||
RUN stack setup
|
||||
RUN stack build --copy-bins
|
||||
|
||||
# Copy the "helloworld-haskell-exe" executable to the image using docker multi stage build
|
||||
FROM fpco/haskell-scratch:integer-gmp
|
||||
WORKDIR /root/
|
||||
COPY --from=builder /root/.local/bin/helloworld-haskell-exe .
|
||||
|
||||
# Expose a port to run our application
|
||||
EXPOSE 8080
|
||||
|
||||
# Run the server command
|
||||
CMD ["./helloworld-haskell-exe"]
|
||||
```
|
||||
|
||||
1. Create a new file, `service.yaml` and copy the following service definition
|
||||
into the file. Make sure to replace `{username}` with your Docker Hub username.
|
||||
|
||||
```yaml
|
||||
apiVersion: serving.knative.dev/v1alpha1
|
||||
kind: Service
|
||||
metadata:
|
||||
name: helloworld-haskell
|
||||
namespace: default
|
||||
spec:
|
||||
runLatest:
|
||||
configuration:
|
||||
revisionTemplate:
|
||||
spec:
|
||||
container:
|
||||
image: docker.io/{username}/helloworld-haskell
|
||||
env:
|
||||
- name: TARGET
|
||||
value: "Haskell Sample v1"
|
||||
```
|
||||
|
||||
## Build and deploy this sample
|
||||
|
||||
Once you have recreated the sample code files (or used the files in the sample
|
||||
folder) you're ready to build and deploy the sample app.
|
||||
|
||||
1. Use Docker to build the sample code into a container. To build and push with
|
||||
Docker Hub, enter these commands replacing `{username}` with your
|
||||
Docker Hub username:
|
||||
|
||||
```shell
|
||||
# Build the container on your local machine
|
||||
docker build -t {username}/helloworld-haskell .
|
||||
|
||||
# Push the container to docker registry
|
||||
docker push {username}/helloworld-haskell
|
||||
```
|
||||
|
||||
1. After the build has completed and the container is pushed to Docker Hub, you
|
||||
can deploy the app into your cluster. Ensure that the container image value
|
||||
in `service.yaml` matches the container you built in
|
||||
the previous step. Apply the configuration using `kubectl`:
|
||||
|
||||
```shell
|
||||
kubectl apply -f service.yaml
|
||||
```
|
||||
|
||||
1. Now that your service is created, Knative will perform the following steps:
|
||||
* Create a new immutable revision for this version of the app.
|
||||
* Network programming to create a route, ingress, service, and load balance for your app.
|
||||
* Automatically scale your pods up and down (including to zero active pods).
|
||||
|
||||
1. To find the IP address for your service, enter
|
||||
`kubectl get svc knative-ingressgateway -n istio-system` to get the ingress IP for your
|
||||
cluster. If your cluster is new, it may take some time for the service to get assigned
|
||||
an external IP address.
|
||||
|
||||
```shell
|
||||
kubectl get svc knative-ingressgateway -n istio-system
|
||||
|
||||
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
|
||||
knative-ingressgateway LoadBalancer 10.23.247.74 35.203.155.229 80:32380/TCP,443:32390/TCP,32400:32400/TCP 2d
|
||||
|
||||
```
|
||||
|
||||
For minikube or bare-metal, get IP_ADDRESS by running the following command
|
||||
|
||||
```shell
|
||||
echo $(kubectl get node -o 'jsonpath={.items[0].status.addresses[0].address}'):$(kubectl get svc knative-ingressgateway -n istio-system -o 'jsonpath={.spec.ports[?(@.port==80)].nodePort}')
|
||||
|
||||
```
|
||||
|
||||
1. To find the URL for your service, enter:
|
||||
```
|
||||
kubectl get services.serving.knative.dev helloworld-haskell -o=custom-columns=NAME:.metadata.name,DOMAIN:.status.domain
|
||||
NAME DOMAIN
|
||||
helloworld-haskell helloworld-haskell.default.example.com
|
||||
```
|
||||
|
||||
1. Now you can make a request to your app and see the result. Replace
|
||||
`{IP_ADDRESS}` with the address you see returned in the previous step.
|
||||
|
||||
```shell
|
||||
curl -H "Host: helloworld-haskell.default.example.com" http://{IP_ADDRESS}
|
||||
Hello world: Haskell Sample v1
|
||||
```
|
||||
|
||||
## Removing the sample app deployment
|
||||
|
||||
To remove the sample app from your cluster, delete the service record:
|
||||
|
||||
```shell
|
||||
kubectl delete -f service.yaml
|
||||
```
|
||||
|
|
@ -0,0 +1,20 @@
|
|||
{-# LANGUAGE OverloadedStrings #-}
|
||||
|
||||
import Data.Maybe
|
||||
import Data.Monoid ((<>))
|
||||
import Data.Text.Lazy (Text)
|
||||
import Data.Text.Lazy
|
||||
import System.Environment (lookupEnv)
|
||||
import Web.Scotty (ActionM, ScottyM, scotty)
|
||||
import Web.Scotty.Trans
|
||||
|
||||
main :: IO ()
|
||||
main = do
|
||||
t <- fromMaybe "NOT SPECIFIED" <$> lookupEnv "TARGET"
|
||||
scotty 8080 (route t)
|
||||
|
||||
route :: String -> ScottyM()
|
||||
route t = get "/" $ hello t
|
||||
|
||||
hello :: String -> ActionM()
|
||||
hello t = text $ pack ("Hello world: " ++ t)
|
|
@ -0,0 +1,15 @@
|
|||
name: helloworld-haskell
|
||||
version: 0.1.0.0
|
||||
dependencies:
|
||||
- base >= 4.7 && < 5
|
||||
- scotty
|
||||
- text
|
||||
|
||||
executables:
|
||||
helloworld-haskell-exe:
|
||||
main: Main.hs
|
||||
source-dirs: app
|
||||
ghc-options:
|
||||
- -threaded
|
||||
- -rtsopts
|
||||
- -with-rtsopts=-N
|
|
@ -0,0 +1,15 @@
|
|||
apiVersion: serving.knative.dev/v1alpha1
|
||||
kind: Service
|
||||
metadata:
|
||||
name: helloworld-haskell
|
||||
namespace: default
|
||||
spec:
|
||||
runLatest:
|
||||
configuration:
|
||||
revisionTemplate:
|
||||
spec:
|
||||
container:
|
||||
image: docker.io/{username}/helloworld-haskell
|
||||
env:
|
||||
- name: TARGET
|
||||
value: "Haskell Sample v1"
|
|
@ -0,0 +1,5 @@
|
|||
flags: {}
|
||||
packages:
|
||||
- .
|
||||
extra-deps: []
|
||||
resolver: lts-10.7
|
Loading…
Reference in New Issue