Health checks in Compose in Docker - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define a health check command in Docker Compose.

Docker

healthcheck:
  test: ["CMD", [1]]

Drag options to blanks, or click blank then click option'

A"echo healthy"

B"curl -f http://localhost"

C"ping -c 1 localhost"

D"curl -f http://localhost/ || exit 1"

Attempts:

3 left

💡 Hint

Common Mistakes

Using a command that always succeeds like 'echo healthy'.

Omitting the 'exit 1' on failure.

The health check command must return 0 on success. Using curl -f http://localhost/ || exit 1 ensures failure if the service is down.

2fill in blank

medium

Complete the code to set the health check interval to 30 seconds.

Docker

healthcheck:
  interval: [1]

Drag options to blanks, or click blank then click option'

A10s

B30s

C1m

D5s

Attempts:

3 left

💡 Hint

Common Mistakes

Using '1m' which is 1 minute, not 30 seconds.

Using a number without 's' suffix.

The interval defines how often the health check runs. Setting it to 30s means every 30 seconds.

3fill in blank

hard

Fix the error in the health check restart policy syntax.

Docker

restart: [1]

Drag options to blanks, or click blank then click option'

Aunless-stopped

Bon-failure

Crestart-always

Dalways

Attempts:

3 left

💡 Hint

Common Mistakes

Using invalid value like 'restart-always'.

Confusing 'on-failure' with 'always'.

The correct restart policy to restart containers unless stopped manually is unless-stopped.

4fill in blank

hard

Fill both blanks to set retries to 5 and timeout to 10 seconds in health check.

Docker

healthcheck:
  retries: [1]
  timeout: [2]

Drag options to blanks, or click blank then click option'

A5

B3

C10s

D30s

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping retries and timeout values.

Using timeout without 's' suffix.

Retries define how many times to retry before marking unhealthy. Timeout is how long to wait for each check. Here, 5 retries and 10 seconds timeout are set.

5fill in blank

hard

Fill all three blanks to create a health check with command 'curl -f http://localhost/', interval 20 seconds, and start period 5 seconds.

Docker

healthcheck:
  test: ["CMD", [1]]
  interval: [2]
  start_period: [3]

Drag options to blanks, or click blank then click option'

A"curl -f http://localhost/ || exit 1"

B20s

C5s

D"curl http://localhost"

Attempts:

3 left

💡 Hint

Common Mistakes

Using incomplete curl command.

Omitting start_period or using wrong format.

The test command must fail if the service is unhealthy. Interval is how often to run the check. Start period is the initial delay before checks start.