asteris-llc/converge

// Copyright © 2016 Asteris, LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package apply

import (
    "fmt"

    "github.com/asteris-llc/converge/executor"
    "github.com/asteris-llc/converge/graph"
    "github.com/asteris-llc/converge/graph/node"
    "github.com/asteris-llc/converge/plan"
    "github.com/asteris-llc/converge/render"
    "github.com/pkg/errors"
    "golang.org/x/net/context"
)

// MkPipelineF is a function to generate a pipeline given an id
type MkPipelineF func(*graph.Graph, string) executor.Pipeline

// ErrTreeContainsErrors is a signal value to indicate errors in the graph
var ErrTreeContainsErrors = errors.New("apply had errors, check graph")

// Apply the actions in a Graph of resource.Tasks
func Apply(ctx context.Context, in *graph.Graph) (*graph.Graph, error) {
    renderingPlant, err := render.NewFactory(ctx, in)
    if err != nil {
        return nil, err
    }
    pipeline := func(g *graph.Graph, id string) executor.Pipeline {
        return Pipeline(g, id, renderingPlant)
    }
    return execPipeline(ctx, in, pipeline, renderingPlant, nil)
}

// PlanAndApply plans and applies each node
func PlanAndApply(ctx context.Context, in *graph.Graph) (*graph.Graph, error) {
    return WithNotify(ctx, in, nil)
}

// WithNotify calls PlanAndApply with a notifier
func WithNotify(ctx context.Context, in *graph.Graph, notify *graph.Notifier) (*graph.Graph, error) {
    renderingPlant, err := render.NewFactory(ctx, in)
    if err != nil {
        return nil, err
    }
    pipeline := func(g *graph.Graph, id string) executor.Pipeline {
        return plan.Pipeline(ctx, g, id, renderingPlant).Connect(Pipeline(g, id, renderingPlant))
    }
    return execPipeline(ctx, in, pipeline, renderingPlant, notify)
}

// Apply the actions in a Graph of resource.Tasks
func execPipeline(ctx context.Context, in *graph.Graph, pipelineF MkPipelineF, renderingPlant *render.Factory, notify *graph.Notifier) (*graph.Graph, error) {
    var hasErrors error

    out, err := in.Transform(ctx,
        notify.Transform(func(meta *node.Node, out *graph.Graph) error {
            renderingPlant.Graph = out
            pipeline := pipelineF(out, meta.ID)

            val, pipelineError := pipeline.Exec(ctx, meta.Value())

            if pipelineError != nil {
                hasErrors = ErrTreeContainsErrors
                return pipelineError
            }
            asResult, ok := val.(*Result)
            if !ok {
                return fmt.Errorf("expected asResult but got %T", val)
            }

            if nil != asResult.Error() {
                hasErrors = ErrTreeContainsErrors
            }

            out.Add(meta.WithValue(asResult))
            return nil
        }),
    )

    if err != nil {
        return out, err
    }

    return out, hasErrors
}