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Add containers questions and exercises

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Added also a couple of storage questions.
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abregman
2022-07-11 01:33:26 +03:00
parent e6946d68f4
commit 842120d428
12 changed files with 779 additions and 310 deletions
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107
exercises/containers/solutions/commit_image.md Normal file
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# Create Images on The Fly
## Requirements
Have at least one image locally (run `podman image ls` to confirm).<br>
If you don't have images locally, run simply `podman pull nginx:alpine`.
## Objectives
1. Run a container using a web server image (e.g. httpd, nginx, ...)
- Bind container's port 80 to local port 80
- Run it in detached mode
- Name should nginx_container
2. Verify the web server runs and accessible
3. Create an HTML file with the following content and copy it to the container to the container to path where it will be accessed as an index file
```
<html>
<head>
<title>It's a me</title>
</head>
<body>
<h1>Mario</h1>
</body>
```
4. Create an image out of the running container and call it "nginx_mario"
5. Tag the container with "mario" tag
6. Remove the original container (container_nginx) and verify it was removed
7. Create a new container out of the image you've created (the same way as the original container)
8. Run `curl 127.0.0.1:80`. What do you see?
9. Run `podman diff` on the new image. Explain the output
## Solution
```
# Run the container
podman run --name nginx_container -d -p 80:80 nginx:alpine
# Verify web server is running
curl 127.0.0.1:80
# <!DOCTYPE html>
# <html>
# <head>
# <title>Welcome to nginx!</title>
# Create index.html file
cat <<EOT >>index.html
<html>
<head>
<title>It's a me</title>
</head>
<body>
<h1>Mario</h1>
</body>
EOT
# Copy index.html to the container
podman cp index.html nginx_container:/usr/share/nginx/html/index.html
# Create a new image out of the running container
podman commit nginx_container nginx_mario
# Tag the image
podman image ls
# localhost/nginx_mario latest dc7ed2343521 52 seconds ago 25 MB
podman tag dc7ed2343521 mario
# Remove the container
podman stop nginx_container
podman rm nginx_container
podman ps -a # no container 'nginx_container'
# Create a container out of the image
podman run -d -p 80:80 nginx_mario
# Check the container created from the new image
curl 127.0.0.1:80
#<html>
#<head>
#<title>It's a me</title>
#</head>
#<body>
#<h1>Mario</h1>
#</body>
# Run diff
podman diff nginx_mario
C /etc
C /etc/nginx/conf.d
C /etc/nginx/conf.d/default.conf
A /run/nginx.pid
C /usr/share/nginx/html
C /usr/share/nginx/html/index.html
C /var/cache/nginx
C /var
C /var/cache
A /var/cache/nginx/client_temp
A /var/cache/nginx/fastcgi_temp
A /var/cache/nginx/proxy_temp
A /var/cache/nginx/scgi_temp
A /var/cache/nginx/uwsgi_temp
# We've set new index.html which explains why it's changed (C)
# We also created the image while the web server is running, which explains all the files created under /var
```

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exercises/containers/solutions/containerized_web_server.md
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1. Run a containerized web server in the background and bind its port (8080) to a local port
2. Verify the port (8080) is bound
3. Reach the webserver from your local host
4. Now run the same web application but bound it to the local port 8080
## Solution
@@ -18,4 +19,6 @@ $ curl http://0.0.0.0:41203 # use the port from the output of the previous comma
<head>
<title>Test Page for the HTTP Server on Red Hat Enterprise Linux</title>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
$ podman run -d -p 8080:8080 httpd
```

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exercises/containers/solutions/sharing_images.md Normal file
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# Sharing Images
## Requirements
Have at least one image locally (run `podman image ls` to confirm).<br>
If you don't have images locally, run simply `podman pull httpd`.
## Objectives
1. Choose an image and create an archive out of it
2. Check the archive size. Is it different than the image size? If yes, what's the difference? If not, why?
3. Copy the generated archive to a remote host
4. Load the image
5. Verify it was loaded and exists on the remote host
## Solution
```
# Save image as an archive
podman save -o httpd.tar httpd
# Check archive and image sizes
du -sh httpd.tar # output: 143MB
podman image ls | grep httpd # output: 149MB
# The archive is obviously smaller than the image itself (6MB difference)
# Copy the archive to a remote host
rsync -azc httpd.tar USER@REMOTE_HOST_FQDN:/tmp/
# Load the image
podman load -i /tmp/httpd.tar
# Verify it exists on the system after loading
podman image ls
```