# OpenSearch Ingestion (OSI) Pipelines for Log Ingestion

## Overview

OpenSearch Ingestion (OSI) is a fully managed, serverless pipeline service that delivers logs from sources like CloudWatch Logs, Fluent Bit, and HTTP into AOS/AOSS without managing infrastructure.

## Creating a Pipeline for CloudWatch Logs

### Step 1: Create Pipeline Role

```bash
aws iam create-role --role-name OSIPipelineRole \
  --assume-role-policy-document '{
    "Version": "2012-10-17",
    "Statement": [{
      "Effect": "Allow",
      "Principal": {"Service": "osis-pipelines.amazonaws.com"},
      "Action": "sts:AssumeRole",
      "Condition": {
        "StringEquals": {"aws:SourceAccount": "<account>"},
        "ArnLike":      {"aws:SourceArn":     "arn:aws:osis:<region>:<account>:pipeline/*"}
      }
    }]
  }'
```

Both `aws:SourceAccount` and `aws:SourceArn` conditions are required to prevent the **confused-deputy** pattern: without `aws:SourceArn`, any OSIS pipeline in the same account could assume this role; the `ArnLike` condition narrows the trust to your OSIS pipelines only. For a single-pipeline trust, replace `pipeline/*` with the specific pipeline name.

Attach policies for CloudWatch Logs source and OpenSearch sink:

```bash
aws iam put-role-policy --role-name OSIPipelineRole --policy-name osis-policy \
  --policy-document '{
    "Version": "2012-10-17",
    "Statement": [
      {"Effect": "Allow", "Action": ["logs:DescribeLogGroups", "logs:FilterLogEvents", "logs:GetLogEvents"], "Resource": "arn:aws:logs:<region>:<account>:log-group:<log-group-name>:*"},
      {"Effect": "Allow", "Action": ["es:DescribeDomain", "es:ESHttpPost", "es:ESHttpPut"], "Resource": "arn:aws:es:<region>:<account>:domain/<domain>/*"}
    ]
  }'
```

### Step 2: Create Pipeline

```bash
aws osis create-pipeline --pipeline-name my-log-pipeline \
  --min-units 1 --max-units 4 \
  --pipeline-configuration-body file://pipeline.yaml
```

> **Tip — pipeline logging for debugging.** OSI pipeline logs may carry sensitive data (document content, field values, query parameters), so create the log group **with KMS encryption first**, then attach it:
>
> ```bash
> # 1. Create the log group with a customer-managed KMS key
> aws logs create-log-group \
>   --log-group-name /aws/vendedlogs/OpenSearchIngestion/my-log-pipeline \
>   --kms-key-id arn:aws:kms:<region>:<account>:key/<key-id>
> aws logs put-retention-policy \
>   --log-group-name /aws/vendedlogs/OpenSearchIngestion/my-log-pipeline \
>   --retention-in-days 30
>
> # 2. Attach it to the pipeline
> aws osis update-pipeline --pipeline-name my-log-pipeline \
>   --log-publishing-options 'CloudWatchLogDestination={LogGroup=/aws/vendedlogs/OpenSearchIngestion/my-log-pipeline},IsLoggingEnabled=true'
> ```

### Pipeline YAML for CloudWatch Logs → AOS

```yaml
version: "2"
cloudwatch-pipeline:
  source:
    cloudwatch_logs:
      acknowledgments: true
      aws:
        sts_role_arn: "arn:aws:iam::<account>:role/OSIPipelineRole"
        region: "<region>"
  processor:
    - date:
        from_time_received: true
        destination: "@timestamp"
  sink:
    - opensearch:
        hosts: ["https://<domain-endpoint>"]
        index: "cwl-%{yyyy.MM.dd}"
        aws:
          sts_role_arn: "arn:aws:iam::<account>:role/OSIPipelineRole"
          region: "<region>"
```

### Pipeline YAML for CloudWatch Logs → AOSS

```yaml
version: "2"
cloudwatch-pipeline:
  source:
    cloudwatch_logs:
      acknowledgments: true
      aws:
        sts_role_arn: "arn:aws:iam::<account>:role/OSIPipelineRole"
        region: "<region>"
  processor:
    - date:
        from_time_received: true
        destination: "@timestamp"
  sink:
    - opensearch:
        hosts: ["https://<collection-endpoint>"]
        index: "cwl-logs"
        serverless: true
        aws:
          sts_role_arn: "arn:aws:iam::<account>:role/OSIPipelineRole"
          region: "<region>"
```

### Step 3: Configure CloudWatch Subscription Filter

```bash
aws logs put-subscription-filter \
  --log-group-name /aws/lambda/my-function \
  --filter-name osi-filter \
  --filter-pattern "" \
  --destination-arn arn:aws:osis:<region>:<account>:pipeline/my-log-pipeline
```

## Common Index Patterns

| Source | Index Pattern | Fields |
|--------|--------------|--------|
| CloudWatch Logs | `cwl-*` | @timestamp, message, log_group, log_stream |
| OTel Collector | `otel-v1-apm-span-*` | traceId, spanId, serviceName, durationInNanos |
| Fluent Bit | `fluent-bit-*` | @timestamp, log, kubernetes.* |

## AOSS Considerations

- Data access policy must grant the pipeline role `aoss:BatchGetCollection` and `aoss:APIAccessAll`
- Network policy must allow OSI pipeline VPC access
- Use `serverless: true` in the sink configuration

## Security Considerations

- Apply least-privilege IAM policies: grant only the specific actions needed (e.g., `es:ESHttpPost`, `es:ESHttpPut`) scoped to the target domain/collection resource ARN.
- All data in transit between OSI pipelines and OpenSearch is encrypted via TLS. Ensure domain or collection enforces HTTPS-only access.
- Use dedicated IAM roles for pipeline execution rather than sharing roles across services.
- Enable CloudTrail at the account level to audit all OSIS API calls (pipeline creation, modification, deletion) for compliance monitoring.