Earlier this year we enhanced our infrastructure to service production loads using multi-cloud deployment, which revealed critical insights about container orchestration in heterogeneous network environments. While Docker Swarm provides robust service abstraction, our production deployments across multiple cloud providers exposed underlying network fabric differences that required architectural consideration.
Network Fabric Heterogeneity and Ingress Routing
We rely on Docker Swarm's ingress routing mesh, which uses an overlay network (typically VXLAN) and operates on the principle of uniform network behavior across cluster nodes. On our primary provider, this model worked seamlessly—traffic routed correctly to services regardless of entry point.
Our secondary provider's network architecture presented specific constraints. We discovered that standard overlay networking encountered incompatibilities with provider-specific firewall rulesets and MTU configurations. The underlying issue centered on VXLAN encapsulation. The provider's default network policies and Security Group configurations were blocking or fragmenting this crucial traffic.
We resolved this by modifying our ingress strategy to accommodate provider-specific network policies.
DNS Resolution in Multi-Provider Container Networks
We encountered one of the most subtle failure modes in multi-cloud architectures: container DNS resolution. Initially, we configured our containers to use public DNS resolvers (e.g., 8.8.8.8) for cross-environment consistency. However, our services suddenly couldn't resolve external endpoints on the secondary provider. The provider's network policy was blocking direct outbound DNS queries from our container network layer, allowing resolution only through the provider's internal DNS servers.
We rearchitected our DNS request flow to resolve this. By configuring Docker's embedded DNS resolver, we delegated DNS operations to the host network stack. Specifically, we set the Docker daemon to use the cloud provider's internal DNS IP address as the upstream resolver. This preserved resolution functionality and authorization by routing all lookups through a sanctioned path within the provider's network security model, eliminating direct container-to-internet DNS queries.
Active-Active Resilience Through Intelligent Traffic Distribution
Rather than implementing a traditional cold-standby model, we deployed active-active load balancing across both cloud providers. We use AWS Route 53's weighted routing policies to enable simultaneous traffic distribution based on provider capacity, while continuous health monitoring ensures automatic failover.
This architecture delivers self-healing capabilities: Route 53 health checks detect provider degradation and automatically redirect traffic to the operational environment without manual intervention. To ensure rapid recovery, we configured a low DNS TTL (Time To Live, e.g., 60 seconds), forcing client resolvers to quickly refresh their records and direct traffic away from the failed endpoint. We've achieved zero-downtime failover with no operational overhead.
Infrastructure Implications
We've learned that multi-cloud deployment extends beyond compute resource distribution. It requires normalizing network fabric differences, understanding provider-specific constraints, and designing for heterogeneous environments from the architecture phase.
Our infrastructure engineering approach ensures that FileSpin's media processing and delivery systems maintain consistent performance regardless of underlying cloud provider characteristics. This allows us to deliver enterprise-grade reliability while abstracting infrastructure complexity from our customers.