Cursor rule

1---
2description: Docker Compose standards Rule
3globs: 
4alwaysApply: false
5---
6 
7## Rule Details
8 
9- **Name:** docker_compose_best_practices
10 
11- **Description:** Enforces best practices in docker-compose files to ensure maintainability, security, and consistency
12 
13## Filters
14- file name: `docker-compose\\.ya?ml$`
15- event: `(file_create|file_modify)`
16 
17## Rejections
18- Conditions:
19  - pattern `^\\s*version\\s*:` – The 'version' field is deprecated in Docker Compose files. Compose files are now version-less by default.
20 
21## Rejections
22- Conditions:
23  - pattern `^(  |\t)` – Inconsistent indentation detected. Use 2 spaces for indentation.
24 
25## Rejections
26- Conditions:
27  - pattern `^\\s*links\\s*:` – The 'links' key is deprecated. Use networks and service names for inter-service communication.
28 
29## Rejections
30- Conditions:
31  - pattern `^\\s*image\\s*:\\s*[^:]+$` – Specify an explicit image tag to ensure consistency.
32 
33## Rejections
34- Conditions:
35  - pattern `^\\s*privileged\\s*:\\s*true` – Running services in privileged mode is discouraged for security reasons.
36 
37## Rejections
38- Conditions:
39  - pattern `^\\s*services\\s*:\\s*[^\\n]+\\n(?!.*\\blimits\\b)` – Define resource limits for each service to prevent resource exhaustion.
40 
41## Suggestions
42- Guidance:
43To adhere to Docker Compose best practices:
44 
451. **Omit the 'version' field**: Compose files are version-less by default.
46```yaml
47   services:
48     web:
49       image: nginx
50```
51 
522. **Use consistent indentation**: Use 2 spaces for indentation.
53```yaml
54   services:
55     web:
56       image: nginx
57```
58 
593. **Avoid 'links' key**: Use networks and service names for service communication.
60```yaml
61   services:
62     web:
63       image: nginx
64       networks:
65         - my-network
66     db:
67       image: mysql
68       networks:
69         - my-network
70   networks:
71     my-network:
72```
73 
744. **Specify explicit image tags**: Prevent unintended updates by defining image tags.
75```yaml
76   services:
77     web:
78       image: nginx:1.21.0
79```
80 
815. **Avoid privileged mode**: Do not use 'privileged: true'. Grant specific capabilities if necessary.
82```yaml
83   services:
84     web:
85       image: nginx
86       cap_add:
87         - NET_ADMIN
88```
89 
906. **Define resource limits**: Prevent services from consuming excessive resources.
91```yaml
92   services:
93     web:
94       image: nginx
95       deploy:
96         resources:
97           limits:
98             cpus: '0.50'
99             memory: '512M'
100```
101 
102Implementing these practices ensures secure, maintainable, and consistent Docker Compose configurations.
103 
104## Metadata
105- Priority: high
106- Version: 1.1
107