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Reworked shell hello world example (#2832) 

* Change event type in Sequence with Broker example (#2897) (#2916)

If the type of the event isn't changed by the last step in the
sequence the event will be resent to the Trigger that targets
the sequence creating an unwanted loop.

Fixes #2851

Signed-off-by: Pierangelo Di Pilato <pierangelodipilato@gmail.com>

* Reworked shell hello world example

* Reworked example to be a "true" shell example that is considerable different than the helloworld-go example
* Added examples for kn usage

(Fixed according to review comments)

Co-authored-by: Pierangelo Di Pilato <pierangelodipilato@gmail.com>
This commit is contained in:
Roland Huß 2020-11-06 16:53:07 +01:00 committed by GitHub
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35
docs/serving/samples/hello-world/helloworld-shell/Dockerfile
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@ -1,32 +1,13 @@
# Use the official Golang image to create a build artifact.
# This is based on Debian and sets the GOPATH to /go.
# https://hub.docker.com/_/golang
FROM golang:1.13 as builder
# Create and change to the app directory.
WORKDIR /app
# Retrieve application dependencies using go modules.
# Allows container builds to reuse downloaded dependencies.
COPY go.* ./
RUN go mod download
# Copy local code to the container image.
COPY invoke.go ./
# Build the binary.
# -mod=readonly ensures immutable go.mod and go.sum in container builds.
RUN CGO_ENABLED=0 GOOS=linux go build -mod=readonly -v -o server
# Use the official Alpine image for a lean production container. # Use the official Alpine image for a lean production container.
# https://hub.docker.com/_/alpine # https://hub.docker.com/_/alpine
# https://docs.docker.com/develop/develop-images/multistage-build/#use-multi-stage-builds
FROM alpine:3 FROM alpine:3
RUN apk add --no-cache ca-certificates
# Copy the binary to the production image from the builder stage. # Update & install netcat (nc)
COPY --from=builder /app/server /server RUN apk update \
COPY script.sh ./ && apk add netcat-openbsd
# Run the web service on container startup. # Copy over the service script
CMD ["/server"] COPY script.sh /
# Start up the webserver
CMD [ "/bin/sh", "/script.sh" ]

204
docs/serving/samples/hello-world/helloworld-shell/README.md
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@ -1,204 +0,0 @@
A simple web app that executes a shell script. The shell script reads an env
variable `TARGET` and prints `Hello ${TARGET}!`. If the `TARGET` environment
variable is not specified, the script uses `World`.
Follow the steps below to create the sample code and then deploy the app to your
cluster. You can also download a working copy of the sample, by running the
following commands:
```shell
git clone -b "{{< branch >}}" https://github.com/knative/docs knative-docs
cd knative-docs/docs/serving/samples/hello-world/helloworld-shell
```
## Before you begin
- A Kubernetes cluster with Knative installed and DNS configured. Follow the
[installation instructions](../../../../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
1. Create a new file named `script.sh` and paste the following script:
```sh
#!/bin/sh
echo Hello ${TARGET:=World}!
```
1. Create a new file named `invoke.go` and paste the following code. We use a
basic web server written in Go to execute the shell script:
```go
package main
import (
"fmt"
"log"
"net/http"
"os"
"os/exec"
)
func handler(w http.ResponseWriter, r *http.Request) {
log.Print("helloworld: received a request")
cmd := exec.CommandContext(r.Context(), "/bin/sh", "script.sh")
cmd.Stderr = os.Stderr
out, err := cmd.Output()
if err != nil {
w.WriteHeader(500)
}
w.Write(out)
}
func main() {
log.Print("helloworld: starting server...")
http.HandleFunc("/", handler)
port := os.Getenv("PORT")
if port == "" {
port = "8080"
}
log.Printf("helloworld: listening on %s", port)
log.Fatal(http.ListenAndServe(fmt.Sprintf(":%s", port), nil))
}
```
1. Create a new file named `Dockerfile` and copy the code block below into it.
```docker
# Use the official Golang image to create a build artifact.
# This is based on Debian and sets the GOPATH to /go.
# https://hub.docker.com/_/golang
FROM golang:1.13 as builder
# Create and change to the app directory.
WORKDIR /app
# Retrieve application dependencies using go modules.
# Allows container builds to reuse downloaded dependencies.
COPY go.* ./
RUN go mod download
# Copy local code to the container image.
COPY invoke.go ./
# Build the binary.
# -mod=readonly ensures immutable go.mod and go.sum in container builds.
RUN CGO_ENABLED=0 GOOS=linux go build -mod=readonly -v -o server
# Use the official Alpine image for a lean production container.
# https://hub.docker.com/_/alpine
# https://docs.docker.com/develop/develop-images/multistage-build/#use-multi-stage-builds
FROM alpine:3
RUN apk add --no-cache ca-certificates
# Copy the binary to the production image from the builder stage.
COPY --from=builder /app/server /server
COPY script.sh ./
# Run the web service on container startup.
CMD ["/server"]
```
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/v1
kind: Service
metadata:
name: helloworld-shell
namespace: default
spec:
template:
spec:
containers:
- image: docker.io/{username}/helloworld-shell
env:
- name: TARGET
value: "Shell Sample v1"
```
1. Use the go tool to create a
[`go.mod`](https://github.com/golang/go/wiki/Modules#gomod) manifest.
```shell
go mod init github.com/knative/docs/docs/serving/samples/hello-world/helloworld-shell
```
## Building and deploying the 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, run these commands replacing `{username}` with your Docker Hub
username:
```shell
# Build the container on your local machine
docker build -t {username}/helloworld-shell .
# Push the container to docker registry
docker push {username}/helloworld-shell
```
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 --filename service.yaml
```
1. Now that your service is created, Knative performs 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. Run the following command to find the domain URL for your service:
```shell
kubectl get ksvc helloworld-shell --output=custom-columns=NAME:.metadata.name,URL:.status.url
```
Example:
```shell
NAME URL
helloworld-shell http://helloworld-shell.default.1.2.3.4.xip.io
```
1. Now you can make a request to your app and see the result. Replace
the URL below with the URL returned in the previous command.
```shell
curl http://helloworld-shell.default.1.2.3.4.xip.io
```
Example:
```shell
curl http://helloworld-shell.default.1.2.3.4.xip.io
Hello Shell Sample v1!
```
> Note: Add `-v` option to get more detail if the `curl` command failed.
## Removing the sample app deployment
To remove the sample app from your cluster, delete the service record:
```shell
kubectl delete --filename service.yaml
```

3
docs/serving/samples/hello-world/helloworld-shell/go.mod
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@ -1,3 +0,0 @@
module github.com/knative/docs/docs/serving/samples/hello-world/helloworld-shell
go 1.14

204
docs/serving/samples/hello-world/helloworld-shell/index.md
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@ -5,4 +5,206 @@ weight: 1
type: "docs" type: "docs"
--- ---
{{% readfile file="README.md" %}} This guide describes the steps required to create the `helloworld-shell` sample app and deploy it to your
cluster.
The sample app reads a `TARGET` environment variable, and prints `Hello ${TARGET}!`.
If `TARGET` is not specified, `World` is used as the default value.
You can also download a working copy of the sample, by running the
following commands:
```shell
git clone -b "{{< branch >}}" https://github.com/knative/docs knative-docs
cd knative-docs/docs/serving/samples/hello-world/helloworld-shell
```
## Prerequisites
- A Kubernetes cluster with Knative installed and DNS configured. Follow the
[installation instructions](../../../../install/README.md).
- [Docker](https://www.docker.com) installed and running on your local machine,
and a Docker Hub account configured.
- (optional) The Knatice CLI client [kn](https://github.com/knative/client/releases) that simplifies the deployment. Alternative you can also use [kubectl](https://kubernetes.io/docs/tasks/tools/install-kubectl/) and apply resource files directly.
## Build
1. Create a new file named `script.sh` and paste the script below. This will run netcat (`nc`) in an endless loop, returning a friendly welcome message.
```shell
#!/bin/sh
while true ; do
echo -e "HTTP/1.1 200\n\n Hello ${TARGET:=World}!\n" | nc -l -p 8080 -q 1;
done
```
1. Create a new file named `Dockerfile` and copy the code block below into it.
```docker
# Use the official Alpine image for a lean production container.
# https://hub.docker.com/_/alpine
FROM alpine:3
# Update & install netcat (nc)
RUN apk update \
&& apk add netcat-openbsd
# Copy over the service script
COPY script.sh /
# Start up the webserver
CMD [ "/bin/sh", "/script.sh" ]
```
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, run these commands replacing `{username}` with your Docker Hub
username:
```shell
# Build the container on your local machine
docker build -t {username}/helloworld-shell .
# Push the container to docker registry
docker push {username}/helloworld-shell
```
## Deploying
1. After the build has completed and the container is pushed to Docker Hub, you
can deploy the app into your cluster.
{{< tabs name="helloworld_shell" default="kn" >}}
{{% tab name="yaml" %}}
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/v1
kind: Service
metadata:
name: helloworld-shell
namespace: default
spec:
template:
spec:
containers:
- image: docker.io/{username}/helloworld-shell
env:
- name: TARGET
value: "Shell Sample v1"
```
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 --filename service.yaml
```
{{< /tab >}}
{{% tab name="kn" %}}
With `kn` you can deploy the service with
```shell
kn service create helloworld-shell --image=docker.io/{username}/helloworld-shell --env TARGET="Shell Sample v1"
```
This will wait until your service is deployed and ready, and ultimately it will print the URL through which you can access the service.
The output will look like:
```
Creating service 'helloworld-shell' in namespace 'default':
0.035s The Configuration is still working to reflect the latest desired specification.
0.139s The Route is still working to reflect the latest desired specification.
0.250s Configuration "helloworld-shell" is waiting for a Revision to become ready.
8.040s ...
8.136s Ingress has not yet been reconciled.
8.277s unsuccessfully observed a new generation
8.398s Ready to serve.
Service 'helloworld-shell' created to latest revision 'helloworld-shell-kwdpt-1' is available at URL:
http://helloworld-shell.default.1.2.3.4.xip.io
```
{{< /tab >}}
{{< /tabs >}}
During the creation of your service, Knative performs the following steps:
- Creates of a new immutable revision for this version of the app.
- Programs the network to create a route, ingress, service, and load balance
for your app.
- Automatically scales your pods up and down (including to zero active pods).
## Verification
1. Run one of the followings commands to find the domain URL for your service.
{{< tabs name="service_url" default="kn" >}}
{{% tab name="kubectl" %}}
```shell
kubectl get ksvc helloworld-shell --output=custom-columns=NAME:.metadata.name,URL:.status.url
```
Example:
```shell
NAME URL
helloworld-shell http://helloworld-shell.default.1.2.3.4.xip.io
```
{{< /tab >}}
{{% tab name="kn" %}}
```shell
kn service describe helloworld-shell -o url
```
Example:
```shell
http://helloworld-shell.default.1.2.3.4.xip.io
```
{{< /tab >}}
{{< /tabs >}}
1. Now you can make a request to your app and see the result. Replace
the URL below with the URL returned in the previous command.
Example:
```shell
curl http://helloworld-shell.default.1.2.3.4.xip.io
Hello Shell Sample v1!
# Even easier with kn:
curl $(kn service describe helloworld-shell -o url)
```
> Note: Add `-v` option to get more details if the `curl` command failed.
## Removing
To remove the sample app from your cluster, delete the service record.
{{< tabs name="service_url" default="kn" >}}
{{% tab name="kubectl" %}}
```shell
kubectl delete --filename service.yaml
```
{{< /tab >}}
{{% tab name="kn" %}}
```shell
kn service delete helloworld-shell
```
{{< /tab >}}
{{< /tabs >}}

35
docs/serving/samples/hello-world/helloworld-shell/invoke.go
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@ -1,35 +0,0 @@
package main
import (
"fmt"
"log"
"net/http"
"os"
"os/exec"
)
func handler(w http.ResponseWriter, r *http.Request) {
log.Print("helloworld: received a request")
cmd := exec.CommandContext(r.Context(), "/bin/sh", "script.sh")
cmd.Stderr = os.Stderr
out, err := cmd.Output()
if err != nil {
w.WriteHeader(500)
}
w.Write(out)
}
func main() {
log.Print("helloworld: starting server...")
http.HandleFunc("/", handler)
port := os.Getenv("PORT")
if port == "" {
port = "8080"
}
log.Printf("helloworld: listening on %s", port)
log.Fatal(http.ListenAndServe(fmt.Sprintf(":%s", port), nil))
}

6
docs/serving/samples/hello-world/helloworld-shell/script.sh
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@ -1,4 +1,4 @@
#!/bin/sh #!/bin/sh
echo Hello ${TARGET:=World}! while true ; do
echo -e "HTTP/1.1 200\n\n Hello ${TARGET:=World}!\n" | nc -l -p 8080 -q 1;
done

4
test/sampleapp/config.yaml
View File

@ -58,11 +58,7 @@ languages:
- "Dockerfile" - "Dockerfile"
- language: "shell" - language: "shell"
expectedOutput: "Hello Shell Sample v1!" expectedOutput: "Hello Shell Sample v1!"
preCommands:
- exec: "cp"
args: "../../docs/serving/samples/hello-world/helloworld-shell/go.mod helloworld-shell_tmp/go.mod"
copies: copies:
- "script.sh" - "script.sh"
- "invoke.go"
- "service.yaml" - "service.yaml"
- "Dockerfile" - "Dockerfile"

23
test/sampleconsistency/sampleconsistency_test.go
View File

@ -18,6 +18,7 @@ package sampleconsistency
import ( import (
"bufio" "bufio"
"fmt"
"os" "os"
"path" "path"
"strings" "strings"
@ -94,12 +95,16 @@ func checkContains(t *testing.T, rl []string, src string) {
best = 0 best = 0
} }
if best != len(sl) { if best != len(sl) {
t.Fatalf("README.md file is missing line %d ('%s') from file '%s'\nAdditional info:\n%s", best, sl[best], src, sampleapp.ActionMsg) t.Fatalf("README.md/index.md file is missing line %d ('%s') from file '%s'\nAdditional info:\n%s", best, sl[best], src, sampleapp.ActionMsg)
} }
} }
func checkDoc(t *testing.T, lc sampleapp.LanguageConfig) { func checkDoc(t *testing.T, lc sampleapp.LanguageConfig) {
readme := path.Join(lc.SrcDir, "README.md") readme, err := getDocFile(lc.SrcDir)
if err != nil {
t.Fatalf("Error: %v.", err)
return
}
rl := readlines(t, readme) rl := readlines(t, readme)
for _, f := range lc.Copies { for _, f := range lc.Copies {
src := path.Join(lc.SrcDir, f) src := path.Join(lc.SrcDir, f)
@ -107,6 +112,20 @@ func checkDoc(t *testing.T, lc sampleapp.LanguageConfig) {
} }
} }
func getDocFile(dir string) (string, error) {
for _, f := range []string{"README.md", "index.md"} {
path := path.Join(dir, f)
_, err := os.Stat(path)
if err == nil {
return path, nil
}
if !os.IsNotExist(err) {
return "", nil
}
}
return "", fmt.Errorf("cannot find README.md or index.md in %s", dir)
}
// TestDocSrc checks content of README.md files, and ensures that the real code of the samples // TestDocSrc checks content of README.md files, and ensures that the real code of the samples
// is properly embedded in the docs. // is properly embedded in the docs.
func TestDocSrc(t *testing.T) { func TestDocSrc(t *testing.T) {